A lithium mixed metal oxide is used as a positive electrode active material in a nonaqueous electrolyte secondary battery such as a lithium secondary battery. A lithium secondary battery has been previously put into practical use as an electric source of cell phones, laptop computers and the like, and further, there are trials of application thereof also in medium or large size applications such as an automobile application and an electric power storage application.
Regarding conventional lithium mixed metal oxides, International publication No. 02/073718 discloses a manganese-nickel-iron coprecipitate compound obtained by adding a sodium hydroxide aqueous solution to an aqueous solution containing manganese nitrate, nickel nitrate and iron sulfate, and a lithium mixed metal oxide obtained by calcining a mixture of the compound and a lithium compound at a temperature of 1000° C., and describes that the oxide has a BET specific surface area of 0.9 m2/g.
However, nonaqueous electrolyte secondary batteries obtained by using the conventional lithium mixed metal oxides, as described above, as a positive electrode active material are not sufficient in applications requiring high power output at high current rate, that is, in an automobile application and an application of power tools such as electrical tools.